1. Field of the Invention.
The present invention relates to a roll, and, more particularly, to a roll tube that is supported exclusively, at least in a radial direction, in an axially central area on a continuous roll support.
2. Description of the Related Art.
Center supported rolls (CSR) are utilized as guide rolls for wires, fabrics, fiber webs, foils or in similar applications.
One center supported roll located in a former of a machine for the production of a fiber web, specifically a paper or cardboard web, serves to improve wire travel through the former. Due to the deflection characteristics, which are diametrically opposed to those occurring with conventional arrangements where the roll tubes are supported by side journals, the negative influences of other rolls upon the wire travel can be compensated, at least partially, by a center-supported roll. This permits, for example, partial compensation for length differentials of a wire loop at the edges rather than at the center.
The dead weight component of a roll tube, as in conventional side supported rolls, causes a positive or a negative spreading effect, depending on the direction of wrap. The difference is that a center supported roll provides a positive spreading effect, whereas a conventional roll causes a negative spreading effect. Preferred installation positions for a center-supported roll are therefore at locations where a large wrap and/or a conventional roll cause a great negative spreading effect.
A disadvantage of such a center supported roll is that it provides only a negligible deflection based on dead weight, particularly if fiber reinforced synthetic material is used for the roll tube. In other words, this arrangement causes only a negligible spreading effect.